Nonsteroidal anti-inflammatory drugs (NSAID's) such as indomethacin, naproxen, ibuprofen, tolectin, fenoprofen and the like have generally been shown to attenuate the biosynthesis of prostaglandins by inhibiting the activity of the enzyme cyclooxygenase. The prostaglandin end-products of the cyclooxygenase pathway are responsible for many of the early signs of inflammation including hyperalgesia, increases in vascular permeability leading to edema, and pyrexia. The activity and potency or the NSAID's in reducing these signs and symptoms is, for the most part, correlated with their ability to inhibit prostaglandin biosynthesis.
The other major pathway of arachidonic acid metabolism is the lipoxygenase pathway. Lipoxygenase products of arachidonate metabolism, the leukotrienes, hydroxyeicosatetraenoic acids (HETES) and hydroperoxyeicosatetraenoic acids (HPETES), have been shown or implicated to be involved in disease states including acute and chronic inflammation, arthritis, allergic and other hypersensitivity disorders, dermatological diseases such as psoriasis, acne, atopic dermatitis, contact sensitivity, eczema and others, cardiovascular disorders secondary to myocardial ischemia or infarction, thromboembolism or vasculitis or platelet aggregation, and hyperalgesic disorders, gynecological disorders such as dysmenorrhea, ocular inflammation, sperm motility or function, and others.
Leukotriene B.sub.4 (LTB.sub.4), another product of the lipoxygenase pathway, as well as HETES and HPETES can mediate induction of other phlogistic substances such as thromboxanes and prostacyclin, is chemotactic to inflammatory cells, and is hyperalgesic. Many of these mediators have been identified in skin, lungs, coronary circulation, eyes, gastrointestinal tract and other organs, and in the synovial fluid of rheumatoid arthritic patients. In chronic inflammatory conditions such as rheumatoid arthritis, it is believed to be the chronic influx of leukocytes, probably mediated by LTB.sub.4, that is the eventual cause of joint erosion.
It is believed that inhibitors of the lipoxygenase pathway could lead to a relatively permanent effect on inflammatory disorders such as rheumatoid arthritis since they could modulate the actual mechanisms of tissue and joint breakdown. Similarly, drugs that could inhibit prostaglandin synthesis via the cyclooxgenase pathway could modulate and reduce early manifestations of inflammation. Pharmacologically active compounds that can inhibit both enzyme pathways at similar concentrations (dual inhibitors) provide a more complete relief for patients suffering from arthritis, hypersensitivity, dermatological, cardiovascular, gastrointestinal, ocular, and gynecological disorders than present drugs that inhibit one pathway, but not the other as is the case for usually used NSAID's that are predominantly inhibitors of the cyclooxygenase (prostaglandin synthesis) pathway.
A number of 1,5-diaryl-3-substituted pyrazoles are reported in the literature. Some of those pyrazoles have been reported to have pharmacological activity.
For example Fulmer et al., J. Het. Chem., 17:799-800 (1980) report the synthesis of 1,3,5-triaryl pyrazoles, as do Foote et al., J. Het. Chem., 7:89-92 (1970), Beam et al., J. Het. Chem., 9:183-185 (1972); Soliman et al., J. Pharm. Sci., 70:606-610 (1981), and Barluenga et al., J.C.S. Chem. Comm., 891 (1979). Soliman et al., J. Pharm. Sci., 70:602-605 (1981) also report synthesis of 3-methyl-1,5-diarylpyrazoles in which the 1-position aryl is a phenylsulfonylurea or thiourea. Of the above reports, only the two reports by Soliman et al. discuss any pharmacological activity for the pyrazoles prepared or for analogs of those pyrazoles, and those materials are reported to have hypoglycemic activity.
Virmani et al., Indian J. Chem., Sect. B. 17B: 472-477 (1979) report the synthesis of 3-omega-alkylaminoalkyl pyrazoles among other compounds. The 1,5-diaryl-3-substituted pyrazoles reported contained a phenyl group at the 1-position, a 4-nitrophenyl at the 5-position, and a (CH.sub.2).sub.n --NHCH.sub.3 group at the 3-position, where n is 3,4 or 5 (3-5). This report stated that the compounds prepared were screened for a number of biological activities, with nine of the ninety-four numbered compounds synthesized having mild anti-inflammatory activity, two others having diuretic activity and two others having weak anti-cancer activity. The above-discussed 1,5-diaryl-3-substituted pyrazoles were not among the compounds reported to have any pharmacological activity.
Vereshchagin et al., Zh. Org. Khim., 7:907-912 (1971) reported the synthesis of 1,5-diaryl-3-substituted pyrazoles. The 3-substituents were reported to be alkoxy alkylene in which the alkoxy radical was methoxy or phenoxy and the alkylene was methylene or isopropylene, while the 1,5-diaryl radicals were unsubstituted phenyl.
Jahn and Wagner-Jauregg, Arzneim-Forsch. (Drug Res.), 24:494-499 (1974) reported the synthesis and some pharmacological activities of 1,5-diaryl-3-substituted-4,5-dihydropyrazoles. The aryl group at the 1-position for each reported compound was phenyl, while the 5-aryl substituent was reported to be phenyl, 4-methoxyphenyl, 3-methoxy-4-hydroxyphenyl, and 2-hydroxyphenyl. The before-mentioned pyrazoles were substituted at the 3-position by bonding to the 3-position of propionic acid or propiohydroxamic acid. These compounds were said to possess antirheumatic activity.
Shawali et al., J. Het. Chem., 13:989-92 (1976); Shawali, J. Het. Chem., 14:375-81 (1977); and Matsumoto et al., Bull. Chem. Soc. Japan, 47: 946-949 (1979) reported the synthesis of 1,5-diaryl-3-subsituted pyrazoles, all of which also included a substituent other than hydrogen at the 4-position on the pyrazole ring. Exemplary 4-position substituents were reported to include cyano, amino, carboethyoxy, and phenylcarbonyl. These reports included no mention of biological activity of the compounds reported.
A series of benzimidoylpyrazoles was reported by Shrof et al., J. Med. Chem., 24:1521-1525 (1981). These compounds were reported to possess activities of sulfonyl urea and biguanide hypoglcemics.
Biere et al., Arch. Phar., 316:608-616 (1983) reported the synthesis of 1,4-diaryl-pyrazole-3-acetic acid derivatives, some of which also contained a an aryl substituent at the 5-position. The synthesized compounds were assayed for use as anti-inflammatory drugs in rats. The compounds assayed that also contained 5-position substituents were reported to be relatively inactive.
A further group of 1,5-diphenyl-4-substituted-pyrazole-3-acetic acids was reported by El-Sayed and Ohta, Bull. Chem. Soc. Japan, 46:1801-1803 (1973). Those compounds were utilized as intermediates in the synthesis of pyrazolo-[4,3-c]-pyridines. Another group of 1,5-diphenyl-4-substituted-pyrazoles, some of which also include methyl, phenyl and carboxymethyl groups at the 3-position, was reported in Al-Saleh et al., J.C.S. Perkin I, 642-645 (1981) The reports of El-Sayed and Ohta and those of Al-Saleh et al. make no mention of the pharmacological properties of the pyrazole derivatives reported. Another group of 1,5-diaryl-3,4-disubstituted pyrazoles and 4,5-dihydro-5-hydroxy pyrazoles was reported in Fusco and Croce, Gazz. Chim. Ital., 101:703-272 (1971).